function popnew=mutation(pop,pmut,n,length)
%變異函數
%pmut為變異概率
k=1;
while k<=n
    rk=rand();
    if rk<pmut
        pos=fix(rand()*2*length)+1;   %隨機產生變異點
        pop(k,pos)=~pop(k,pos);       %對變異點進行變異
    end
    k=k+1;
end
popnew=pop;